1. Field of the Technology
The present invention relates to the communication field, and more particularly to a multicast broadcast technology in a worldwide interoperability for microwave access (WiMAX) system.
2. Background of the Invention
Worldwide interoperability for microwave access (WiMAX), as a wireless metropolitan area network (MAN) technology, is applicable for wireless broadband access. FIG. 1 shows an end-to-end reference model of a WiMAX system. Referring to FIG. 1, the WiMAX system mainly includes a mobile station (MS)/subscriber station (SS), an access service network (ASN), and a connectivity service network (CSN).
The ASN is defined as a set of network functions for providing wireless access services to WiMAX subscriber terminals, and includes a base station (BS) and a network element, ASN gateway (ASN-GW). One ASN may be shared by a plurality of CSNs.
The main functions of the ASN include functions of the BS and functions of the ASN-GW. The functions of the BS include: providing an L2 connection between the BS and an SS/MS, radio resource management, measurement and power control, and air interface data compression and encryption. The functions of the ASN-GW include: providing a proxy function for authentication, authorization, and accounting functions of the SS/MS; supporting network discovery and selection of a network service provider (NSP); and providing a relay function (e.g. IP address assignment) of L3 information for the SS.
The CSN is defined to provide IP connectivity services to WiMAX subscriber terminals. The CSN mainly provides the following functions: IP address assignment for the SS/MS; Internet access; authentication, authorization, and accounting (AAA) proxy or server; subscriber-based authorization control; providing a tunnel from the ASN to the CSN; accounting of WiMAX subscribers and settlement between operators; providing a tunnel between the CSNs during roaming; inter-ASN handover; and various WiMAX services (e.g. location-based service, multimedia broadcast/multicast service (MBMS), and IP multimedia subsystem (IMS) service).
The MS/SS is a user equipment, with which a subscriber accesses a WiMAX network.
Generally, the communication refers to a communication carried out between one node and another node. However, with the increasing of the user requirements and introduction of multimedia, a new transmission mode is required, for example, including point-to-multipoint communication and even including multipoint-to-multipoint communication. In order to support such modes and utilize the communication resources effectively, i.e., multiplexing some critical communication resources such as air interface bandwidth, a connection ID (CID), and a transmission tunnel of an access network, a multicast broadcast service (MBS) has been proposed in the conventional art.
In the traditional concept of communication, multicast and broadcast are technologies for transferring a data from one data source to a plurality of targets. The MBS provides a specification for sending a data from one data source to a plurality of subscribers in a mobile network, thus achieving sharing of network resources and increasing the utilization of network resources, especially air interface resources.
It should be noted that, the MBS can not only multicast and broadcast low-rate text message services, but also multicast and broadcast high-speed multimedia services, such as video on demand, television broadcasting, video conference, online education, and interactive game and the like.
The protocol in the prior art supports air interface signaling and data transmission of the MBS. Transmission modes of the MBS may be classified into a single-BS mode and a multi-BS mode. The concept of MBS zone is defined under the multi-BS mode. One so-called MBS zone refers to one set of BSs that shall satisfy a condition: the multicast connection identifier (MCID) and the security association (SA) adopted when sending an MBS data must be consistent with each other. In the prior art, there are no detailed descriptions about the single-BS mode, but corresponding descriptions about how a BS sends an MBS data, how an MS receives the MBS data, and how the BS notifies the MS that the MBS data interested by the MS has been sent under the multi-BS mode can be found.
Descriptions about the air interface in the existing system are mainly provided as follows.
Firstly, a downlink map (DL-MAP) message broadcasted on a broadcast CID includes zero to one or more multicast broadcast service map information elements (MBS-MAP-IEs). Each entry on each MBS-MAP-IE is identified by an MBS zone ID.
Secondly, one MBS-MAP-IE identifies physical resources for broadcasting a multicast broadcast service map (MBS-MAP) message on the air interface, which directly indicates physical resources of the MBS under the single-BS mode.
Thirdly, one MBS-MAP message may include zero to one or more multicast broadcast service data information elements (MBS-DATA-IEs) or extended MBS-DATA-IEs. Physical parameters of the MBS-DATA-IEs may be consistent with each other or not depending upon a network side. However, one MBS-DATA-IE merely has one physical parameter set.
Fourthly, one MBS-DATA-IE includes one or more MCIDs. One MBS-DATA-IE is required to include one or more MCIDs in order to reduce a length of the MBS-MAP message, in which all MCIDs corresponding to the MBS data with the same downlink interval usage code (DIUC) are indicated in one MBS-DATA-IE. As for data transmission, medium access control-protocol data units (MAC-PDUs) with the same DIUC are transmitted in the same physical resources. Although being mixed up within the physical resources, different MBS data may be separated from one another in an upper portion of a MAC layer according to MCIDs in MAC-PDU headers. Not all MCIDs correspond to the same MBS, but each MCID corresponds to one MBS.
Fifthly, in an extended MBS-DATA-IE, one MCID further includes one or more logical channel IDs (LCIDs). The LCIDs are used in the air interface to inform the MS whether there are contents interested by the MS or not in the currently indicated MBS data.
In addition, zero to one or more MBS zone IDs may be carried in a dynamic service deletion (DSD) process. MBS content IDs, MCIDs, and LCIDs are one-to-one correspondent to one another. The MBS content IDs are used to identify upper layer data flows borne by a service flow (SF) in a WiMAX access network.
The DL-MAP message indicates physical resources for sending a next MBS-MAP message, but does not distinguish MCIDs and LCIDs carried in the MBS-MAP message. The MBS-DATA-IE also has an indication for physical resources for sending a next MBS-MAP message. Different from the indication in the DL-MAP, the MBS-MAP message herein is a special MBS-MAP message that must include one MBS-DATA-IE having the same MCID and LCID as the current MBS-DATA-IE. In this manner, the MS does not need to receive DL-MAP messages one by one, and can get to know a time point for sending the next interested MBS-MAP message simply based on the current MBS-MAP-IE.
In addition, the MBS-DATA-IE also has a change indication. If no change is indicated, the MBS data is directly received; otherwise, a new MBS-DATA-IE needs to be parsed, so as to update relevant MBS information of the MS.
Two MBS service modes are defined in existing air interface standards, that is, a single-BS service mode and a multi-BS service mode. In the multi-BS service mode, a connection ID of an air interface link layer needs to be unique within the whole MBS zone. In the single-BS service mode, a connection ID of an air interface link layer only needs to be unique within a BS. The connection ID of an air interface link layer may be either a CID or an MCID.
One air interface link layer connection can bear one or more upper layer data flows, and it is defined in the standards to adopt MBS content IDs to distinguish different upper layer data flows borne by an air interface link layer connection. When one air interface link layer connection bears a plurality of contents, LCIDs are used in the link layer for identification, so as to indicate the contents borne in the link layer packets. However, in the existing standards, LCIDs assigned by a network side entity cannot be notified to the MS through a defined link layer management message in advance. Moreover, no specific methods for assigning MCIDs, MBS content IDs, and LCIDs as important IDs in the MBS system are provided in the prior art.